Systemic Lupus Erythematosus (SLE) is an acquired, multiorgan, autoimmune disease. Clinical presentation is extremely variable and heterogeneous. It has been shown that SLE itself is an independent risk factor for developing both arterial and venous thrombotic events since SLE patients have an Odds Ratio (OR) for thrombosis that varies depending on the clinical and laboratory characteristics of each study cohort. The risk of developing a thrombotic event is higher in this setting than in the general population and may further increase when associated with other risk factors, or in the presence of inherited or acquired pro-thrombotic abnormalities, or trigger events. In particular, a striking increase in the number of thrombotic events was observed when SLE was associated with antiphospholipid antibodies (aPL). The presence of aPLs has been described in about 50% of SLE patients, while about 20% of antiphospholipid syndrome (APS) patients have SLE. While APS patients (with or without an autoimmune disease) have been widely studied in the last years, fewer studies are available for SLE patients and thrombosis in the absence of APS. Although the available literature undoubtedly shows that SLE patients have a greater prevalence of thrombotic events as compared to healthy subjects, it is difficult to obtain a definite result from these studies because in some cases the study cohort was too small, in others it is due to the varied characteristics of the study population, or because of the different (and very copious) laboratory assays and methods that were used. When an SLE patient develops a thrombotic event, it is of great clinical relevance since it is potentially life-threatening. Moreover, it worsens the quality of life and is a clinical challenge for the clinician.